It is well recognized in the art of vehicle suspension design and especially in the art of designing suspensions for trucks, trailers and so-called semi-trailers of the medium and heavy duty type (which vehicles exhibit a rather high center of gravity), that an essential safety feature of any such suspension design must have the requisite amount of “roll stability,” a term used herein according to its well-understood meaning in the art of vehicle (and suspension) design.
Absent the requisite amount of roll stability, i.e., this important safety feature for highway and general operation safety, a truck, trailer or semi-trailer having a relatively high center of gravity compared, for example, to an ordinary automobile, is subject to the problem known as “roll over,” e.g., rolling or tipping over when driving around a curve or cornering, or in a high speed braking situation, etc. (particularly when on a downgrade and, more particularly, if fully loaded so as to increase its effective center of gravity for roll over purposes).
For this reason, various attempts, some successful and some only partially successful, have been made to achieve an acceptable level of “roll stability” (i.e., as defined above, the ability to resist roll over during use). In this respect, an example of a suspension which is highly roll stable is disclosed in U.S. Pat. No. 6,527,286 having an overlapping inventive entity herewith. In this patented suspension, a high level of roll stability is achieved by employing a special fabricated structure located between the opposing, longitudinal side rails of the vehicle (e.g., truck, semi-trailer, etc.). As disclosed in this patent, such a roll stabilizing structure may assume various different configurations, such as, for example, a true box-like structure, an “X” shape or a “Y” shape. For convenience, these structures may be conveniently referred to generically as a “torque box.” In each instance, these torque boxes extend substantially and often completely between opposing longitudinal side, frame rails of the vehicle.
While highly effective to prevent roll over, i.e., obtain a high level of roll stability, these torque boxes consume, by their nature, design, and location, a large amount of space between the frame rails of the vehicle, under the truck or semi-trailer body which could otherwise be used more advantageously for other componentry, such as air tanks, dump body hoists, drive shafts, etc. Moreover, these suspensions still require, despite the use of a torque box between the frame rails, the use of radius rods for suspension alignment and stability, including wheel tracking during travel.
Thus, the use of these so-called “torque boxes,” while highly advantageous to prevent roll over and achieve both roll stability and a high level of safety, as well as ride comfort, nevertheless, add substantial weight to the vehicle. Such added weight (1) may often reduce the amount of cargo that can be lawfully carried under existing highway weight limit laws; (2) reduce fuel economy; and (3) reduce the space available for locating other desirable auxiliary componentry under or between the frame rails of the vehicle.
In view of the above, it is apparent that there exists a need in the art for a new suspension design which achieves or exceeds the desirable level of roll stability and safety of the above-described prior art, e.g., of the suspensions disclosed in the aforesaid U.S. Pat. No. 6,527,286, but which does so in a manner that reduces weight and decreases the space taken up by the roll stabilizing componentry when compared to the aforesaid '286 patented suspension.
It is a purpose of this invention to fulfill this need in the art, as well as other needs in the art that will become more apparent to the skilled artisan once given the following disclosure: